Portable apparatus for dressing grinding wheels

ABSTRACT

Portable apparatus for use in dressing the periphery of a grinding wheel mounted on a grinder having a horizontally disposed shaft driven by an electric motor. The apparatus has a U-shaped frame with parallel elongated guides mounted in spaced relation to the shaft by a pair of arms spaced apart on the guides and each rotatably carrying a conical centering pin which engages in a central recess in each end of the shaft to thereby align the frame with the shaft so that a dressing tool mounted in a holder carried on the guides may be displaced across the periphery of the wheel and parallel to its mounting shaft. In addition, the frame is restrained against pivotal movement when the tool engages the rotating grinding wheel by means of a support strut extending toward the base of the grinder from the guides.

United States Patent David A. Crockett Buckingham;

Ellis M. Landis, Berwyn, both of, Pa. 877,175

Nov. 17, 1969 June 8, I971 Crockett Machine Products Co. Warrington, Pa.

lnventors Appl. No. Filed Patented Assignee References Cited UNITED STATES PATENTS 8/1970 "Stoner.....

l/1931 Norton Primary Examiner- Harold D. Whitehead AllomeyHowson and Howson ABSTRACT: Portable apparatus for use in dressing the periphery of a grinding wheel mounted on a grinder having a horizontally disposed shaft driven by an electric motor. The apparatus has a U-shaped frame with parallel elongated guides mounted in spaced relation to the shaft by a pair of arms spaced apart on the guides and each rotatably carrying a conical centering pin which engages in a central recess in each end of the shaft to thereby align the frame with the shaft so that a dressing tool mounted in a holder carried on the guides may be displaced across the periphery of the wheel and parallel to its mounting shaft. In addition, the frame is restrained against pivotal movement when the tool engages the rotating grinding wheel by means of a support strut extending toward the base of the grinder from the guides.

PATENTED JUN 8 mm SHEET 2 0F 3 vsmons: CKETT IN CRO LANDIS WfazuW "[lhllllil ATT'YS,

PATENTEDJUN 8:971 3,583,382

SHEET 3 UF 3 F IG. IO.

PORTABLE APPARATUS FOR DRESSING GRINDING WHEELS The present invention relates to apparatus for performing operations on the periphery of rotary members, and more particularly, the present invention relates to portable apparatus for use in dressing the periphery of grinding wheels.

Grinding wheels tend to accumulate foreign matter in use. At present, accumulated foreign matter is removed from the periphery of a grinding wheel by means of a dressing tool which is engaged thereagainst as the wheel rotates. On relatively large grinding machines, the dressing tool is customarily mounted in registry with the grinding wheel by a bracket which enables the tool to be periodically engaged thereagainst to dress the wheel periphery; however, on relatively small grinders, the dressing tool is held manually in engagement with the grinding wheel to dress the wheel periphery. Although the manual wheel-dressing procedure is effective to remove foreign matter; nevertheless, unless skill and caution is exercised, the periphery of the wheel tends to become rounded or otherwise misshapen. As a result, the effectiveness of the grinding wheel may be impaired, and its operational life may be shortened.

In view of the foregoing, it is a primary object of the present invention to provide novel apparatus for use in dressing a grinding wheel.

It is another object of the present invention to provide portable wheel-dressing apparatus which is adjustable to accommodate grinding wheels of various diameters and which may be used on grinders having wheel drive shafts of various lengths.

As a further object, the present invention provides improved apparatus which enables a person having a minimum of skill to dress a grinding wheel properly.

It is a still further object of the present invention to provide portable wheel-dressing apparatus which does not have a tendency to misshape the peripheral surface of a grinding wheel when it is used by a relatively unskilled person.

More specifically, the present invention provides portable wheel-dressing apparatus for use with a grinder having a pair of grinding wheels mounted on opposite ends of a horizontally disposed, electric motor shaft. The apparatus has guide means extending across the front of the grinder parallel to the shaft and a pair of arms which project past the ends of the shaft from the guide means to form therewith a U-shaped frame. Each of the arms rotatably carries bearing means in the form of a conical pin for engaging in a central recess in each end of the shaft to mount the arms thereto and thereby align the frame with the grinding wheels. The wheels are dressed by a dressing tool carried in a holder which is mounted to slide in alternate directions on the guide means and across the periphery of the wheels, and the frame is supported against rotation on the front of the grinder by means of a strut clamped to the guide means and depending therefrom. Radial adjustment means is also provided on the arms to mount the conical pins at selected locations thereon to accommodate grinding wheels of various diameters. In addition, axial adjustment means is provided to mount one of the arms for axial displacement on the guide means so that the spacing therebetween may be adjusted, and connecting means is provided to prevent relative angular displacement between the arms when the arm spacing is being adjusted so that the apparatus may accommodate grinders having motor shafts of various lengths.

These and other objects, features and advantages of the present invention should become apparent from the following description when taken in conjunction with the accompanying drawings in which:

FIG. I is a plan view of a grinder mounting portable wheeldressing apparatus embodying the present invention;

FIG. 2 is an end elevational view of the wheel-dressing apparatus of FIG. 1;

FIG. 3 is an enlarged perspective view of the wheel-dressing apparatus of FIGS. 1 and 2 dismounted from the grinder to illustrate its frame having a pair of arms and a supporting strut projecting leftward from elongated guide means on which is slidably mounted a tool holder carrying a dressing tool;

FIG. 4 is an enlarged view of a centering pin which engages in a central recess in the left-hand end of the wheel shaft on the grinder as indicated by the broken lines 4-4 in FIG. 3;

FIG. 5 is a perspective view ofa portion of the centering pin of FIG. 4;

FIG. 6 is an enlarged view ofa centering pin for engaging in a central recess in the right-hand end of the wheel shaft on the grinder;

FIG. 6a is a fragmentary view of a portion of the means for mounting the ring-hand centering pin onto its mounting arm;

FIGS. 7 and 8 are enlarged sectional views taken along lines 7-7 and 8-8 of FIG. 3 to illustrate construction details of the tool holder;

FIG. 9 is a partially sectioned, side elevational view of a modified tool holder having an operator which, upon rotation, displaces the holder on a threaded member of the guide means;

FIG. 9a is a sectional view taken along line 9a-9a of FIG. 9;

FIG. 10 is a top plan view of a modified embodiment of the wheel-dressing apparatus of the present invention;

FIG. 11 is a front elevational view of the wheel-dressing apparatus of FIG. I0

FIGS. 12 and 13 are sectional views taken along lines 12-12 and 13-13 of FIGS. 11 and 12 respectively to illustrate a modified tool holder;

FIG. 14 is a view taken along line 14-14 of FIG. 12 to illustrate a modified wheel-dressin g tool; and

FIG. 15 is an elevational view of the right-hand end of the apparatus illustrated in FIG. 10.

Referring now to the drawings, there is illustrated in FIGS. 1 and 2 a conventional grinder 10 having a pair of grinding wheels 11 and 12 secured to the ends of a shaft 13 of an electric motor 14. The motor 14 has a base 15 which is securely fastened to the top of a pedestal 16 to support the grinder at a convenient working elevation. For safety purposes, the wheels are enclosed over a substantial portion of their peripheries by covers 17 and 18; however, the covers are open on the front to expose the wheels and they are open on their sides at 17a and 18a respectively to expose the ends of the shaft 13. In addition, each wheel, as shown on the left-hand wheel 12 in FIG. 1, has a transparent eyeshield 19 mounted on its cover to overlie a workpiece rest 20 on the front of the grinder 10.

At present, it is customary for a workman in dressing a grinding wheel, for example the wheel 12, to position a dressing tool on the workpiece rest 20 and displace the tool in alternate directions across the periphery of the wheel as it rotates. In order to dress the wheel without rounding or otherwise misshaping its periphery, care must be exercised even by a skilled workman. When dressing is attempted by a person of lesser skill, the wheel may be irreparably damaged.

According to the present invention, the aforementioned difficulties are avoided when a dressing tool is displaced across the periphery of a grinding wheel in a path parallel to the rotational axis of the shaft on which the grinding wheel is mounted. To this end, a dressing tool 23 (FIG. 3) is mounted in a holder 24 which is carried in a portable frame 25 mounted on the front of the grinder 10 as illustrated in FIGS. 1 and 2. As may be seen therein, the frame is U-shaped in a horizontal plane and has means for guiding the tool 23 parallel to the shaft 13 and means for mounting the tool-guiding means in spaced parallel relation to the shaft 13. In the embodiment of FIG. 3, the tool-guiding means is a hollow elongated member or rod 26 which slidably mounts the tool holder 24 thereon with the tool 23 projecting outwardly from the holder normal to the rod 26 to engage the grinding wheel 11. The rod 26 extends beyond the ends of the shaft 13 and is disposed at an elevation between the eyeshield 19 and the workpiece rest 20 so that sparks and foreign matter generated when the wheel is being dressed are deflected safely away from the workman using the apparatus.

In the present instance, the guide rod 26 is mounted in spaced relation to the shaft 13 by means of a pair of arms 27 and 28 carried in spaced parallel relation on the rod 26 and extending at right angles outwardly therefrom past the ends of the shaft 13 for mounting thereto. As may be seen in FIG. 2, each of the arms 27 and 28 is slightly offset downwardly at its rearward end to cause the line of action of the dressing tool to be directed radially inward toward the center of the wheel II. In order to conserve weight and to enhance the portability of the apparatus, the arms 27 and 28 are preferably of cast aluminum construction and the rod 26 is steel. Additional strength and rigidity is imparted to the aluminum arms and the frame 25 by longitudinally extending ribs 27a and 28a extending along each arm 27 and 28 respectively at right angles to the planes thereof.

When the motor I4 is energized, the grinding wheel II rotates in a counterclockwise direction (see FIG. 2). As a result, a downward force is exerted on the tool 23, on its holder 24, and on the frame 25. In order to securely support the frame 25 to prevent it from pivoting about the rotational axis of the shaft 13, supporter strut means 58 is provided. As may be seen in FIG. 2, the strut means 38 inclines forwardly and downwardly toward the base ll of the grinder 110 from the frame 25 to thereby support the frame 25 below the eyeshield 19. In the embodiment of FIG. 3, the strut means 30 is releasably secured to the rod 26 by means of a C-type clamping element 31 which is pivotally connected at its lower end to a bifurcated leg or yoke 32 in which is threadedly carried a threaded shaft 33. The threaded shaft 33 projects axially downward from the leg 32 and tapers to a point 34 at its lowermost end so that it engages the base ll5 of the grinder without slipping. The mounting elevation of the frame on the front of the grinder I0 is adjusted to compensate for differences in wheel and motor size among grinders by rotating the shaft 33 in the desired direction and locking it in position with a locknut 35. In normal use, the strut means is clamped to the rod 26 near its center so that the strut means 30 is maintained out of the operative path of the tool holder 24 as it is being displaced in alternate directions across the periphery of either wheel II or 112.

In accordance with the present invention, bearing means is carried on the arms 27 and 28 for engaging the ends of the shaft to cause the guide rod to be automatically disposed parallel to the shaft 13 when the frame 25 is mounted on the grinder l0. To this end, the shaft-engaging means comprises a pair of conically shaped pins or needle members and 41 mounted to project inwardly from the inside of the arms 27 and 28 respectively. As may be seen in FIG. 3, the apexes of the pins 40 and 41 are disposed in a line parallel to the rod 26 so that the rod is automatically mounted properly when they project through the openings 17a and 18a in the wheel covers and are engaged in central recesses in the ends of the shaft 13.

In order to reduce the torque applied to the frame through the conical pins when the shaft 13 rotates, the pins 40 and 4ll are mounted to their respective arms through low-friction ball bearing assemblies 42 and 43 respectively (see FIGS. 4 and 6, Sheet 2). The bearing assemblies 42 and 43 are mounted to the arms by keepers 44 and45 which engage the outer races of the bearing assemblies and which have stems 46 and 47 received in bores 48, 48 and 49, 49 in the arms 27 and 28 respectively. As may be seen in FIG. 3, the stem-receiving bores are spaced apart along the length of the arms to enable the keepers to be mounted in selected locations thereon for enabling the frame 25 to be adjusted to accommodate grinders having wheels of different diameters. In the present instance, the pins 40 and M have rearwardly projecting necks 40a and 410 which are pressed into the bearing assemblies 42 and 43 respectively to thereby mount the pins therein.

For the purpose of enabling the frame to be readily adjusted, means is provided to releasably latch the keeper stems 46 and 47 in their mounting bores. As may be seen in FIG. 6, a

latching action is provided for the right-hand keeper by a threaded element, in the present instance a dog or screw 50, which is threaded into the bottom of the arm 28 and which projects upwardly into a channel 51 in the lower periphery of the keeper stem 47. The channel 51 has a traverse portion 51a extending between a rearwardly open portion 51b and a detent Sllc (FIG. 6a) in which the screw is normally engaged. The channel portion 511!) extends rearwardly along the stem 47 and is open at its rearward end to enable the keeper to be displaced axially in its mounting bore and rotated to cause interengagement between the screw 50 and the detent 510. In order to prevent the keeper 45 from being inadvertently unlatched, the detent 510 is biased against the screw 50 by resilient means, in the present instance a spring washer 52 which surrounds the stem 47. Thus, the right-hand keeper may be removed from the arm 28 simply by pushing it theretoward and rotating it through a portion of a turn to cause the screw 58 to disengage its detent, and the right-hand keeper may be mounted in another bore 49 on the arm by reversing this procedure.

In order to securely mount the frame 25 on the grinder 10 in a manner which also enables it to be readily dismounted therefrom, the left-hand pin or shaft-engaging member 40 is mounted for displacement toward and away from its mounting arm so that the spacing between the pins may be increased or decreased. To this end, the left-hand keeper 44, like the righthand keeper 45, has a channel 55 in its lower periphery with a transverse portion 55a (FIG. 5) which is engaged by a screw 56 projecting upwardly thereinto from the bottom of the arm 27. The channel 55 has a rearwardly extending portion 55b which is open at its rearward end and has a forwardly extending portion 550 which enables the keeper 44 to be displaced leftward into the position shown in broken lines in FIG. 4 to increase the spacing between the pins. The screw 56 is normally maintained aligned with the forward portion 550 of the channel 55 in engagement in the transverse portion 55a by means of a resilient member, in the present instance, a compression spring 57 surrounding the stem 46 and biasing the keeper 44 rightward into the full line position shown in FIG. 4. With this structure, a workman may mount and dismount the frame 25 simply by displacing the keeper 44 toward its mounting arm and holding it adjacent thereto against the bias of the spring 46 while installing the frame 25 on the grinder 18. The bias of the spring 57 permits displacement of the screw 56 in the forward portion 550 of the channel 55 to maintain the pins 48 and 4K in engagement with their respective ends of the shaft 13 and securely mount the frame 25 on the grinder accommodating to small differences in length. The pin 40 may be mounted in any of the bores 48 in a manner similar to the mounting of the keeper 4! in the bore 49.

In order to enable the apparatus of the present invention to accommodate a plurality of grinders having shafts of widely different lengths, means is provided to mount the arms 27 and 28 for relative movement on the guide rod 26 to adjust the spacing therebetween. To this end, the left-hand arm 27 is anchored on the rod 26 and the right-hand arm 28 is mounted for displacement on the rod toward and away from the lefthand ann 27. As may be seen in FIG. 3, Sheet 1, the righthand arm 28 receives the rod 26 in a through bore, and is releasably locked onto the rod 26 by means of a threaded fastener 60 threaded into the top of the arm 28. The fastener 60 is operable upon rotation in the clockwise direction (FIG. I) to engage the rod in its mounting bore, and is operable upon rotation in the counterclockwise direction to disengage the rod therein. Thus, the spacing between the arms may be adjusted and the arm 28 locked in position simply by rotating the fastener 66 in the required direction.

When the right-hand arm 28 is unlocked from the rod 26 during adjustment of the frame 25, there is a tendency for it to pivot on the rod 26 and to thereby move out of aligned relation with the left-hand arm 27. In addition, when the tool 23 is engaged with either of the grinding wheels, the tool holder 24 tends to pivot on the guide rod 26. In order to eliminate these undesirable effects, means is provided in the frame 25 to engage and extend between the arms 27 and 28 for restraining the arms 27 and 28 and the holder 24 against pivoting with respect to one another. In the embodiment of FIG. 3, the restraining means comprises a solid elongated bar 70 disposed parallel to the rod 26 and outwardly thereof. The bar 70 is slidably received in through bores in the arms 27 and 28, and the bar 70 is secured to the arms by means of knurled bolts 71 and 72 which are threaded into the bottom of the arms 27 and 28 respectively and which operate upon counterclockwise rotation (FIG. 3) to engage the bar 70 and which operate upon clockwise rotation to disengage the bar 70. In normal use, the left-hand bolt 71 is kept tightly engaged with the bar 70 and the right-hand bolt is rotated along with the fastener 60 when it is desired to adjust the arm spacing. In this manner, the bar 70 prevents the right-hand arm 28 from pivoting on the rod 26.

When a grinding wheel is being dressed, foreign matter and particles of abrasive material are removed from the grinding wheel, causing it to decrease in diameter. In order to enable the workman to adjust the location of the tool 23 to compensate for this, means is provided to mount the tool 23 in the holder 24 for displacement in a path normal to the guide rod 26 and toward and away from the grinding wheel. To this end, the tool 23 has a cylindrical body which is slidably received in a cylindrical bore in the tool holder 24 (see FIG. 7). In the present instance, the tool 23 is displaced axially in its mounting bore by means of a threaded element 80 journaled in the tool holder 24 and threadedly received in an internally threaded bore 82 in the rearward end of the tool body. The element 80 is rotated by means of a knurled knob 83 secured thereto by a setscrew 84, and the tool is prevented from rotating in its mounting bore when the knob 83 is rotated by means of a vertically disposed dog or screw 85 projecting downwardly into a slot 86 extending lengthwise in the upper periphery of the tool body. The displacement of the tool into and out of the holder 24 is limited by means of abutments 87 and 88 located at the opposite ends of the slot 86 to engage the screw 85 upon continued rotation of the knob in either the clockwise or counterclockwise direction (FIG. 3). In the present instance, the spacing between the abutments is greater than the spacing between the keeper mounting bores 48, 48 and 49, 49 in the arms 27 and 28 so that an overlap in the total radial adjustability of the apparatus is provided. Thus, with this structure, the workman may make minute adjustments in the path of displacement of the tool 23 across the periphery of the wheels simply by rotating the knob 83 in the proper direction. 1

The tool holder 24 is constructed to slide freely on the rod 26 and bar 70 comprising the guide means. For this purpose, oilless bearing bushings 26a and 70a are provided in the tool holder 24 for engaging the rod 26 and bar 70 to thereby reduce sliding friction therebetween. Also, resilient wipers 26b and 70b (FIGS. 3 and 8) surround the rod 26 and bar 70 at each end of the bushings 26a and 70a to prevent foreign matter from entering therein and causing the bushings and guide means to wear.

In use, the conical centering pins 40 and 41 are mounted on the arms 27 and 28 at locations corresponding to the diameter of the grinding wheels to be dressed. The spacing between the arms 27 and 28 is adjusted to correspond approximately to the length of the wheel-mounting shaft on the grinder, and the strut means 30 is also adjusted to dispose the frame 25 in its operating position on the grinder. After the frame 25 is properly adjusted and mounted on the grinder, the knob 83 on the tool holder 24 is rotated to cause the tool 23 to engage the periphery of the wheel to be dressed. The wheel may then be dressed by displacing the tool holder 24 thereacross and making minute adjustments in the depth of engagement of the tool 23 by rotating the knob 83 as desired.

In a modified embodiment of the present invention, means is provided to positively displace a dressing tool 123 (FIGS. 9 and 9a) across the periphery of a grinding wheel..To this end,

a threaded bar is provided in lieu of the smooth bar 70 in the embodiment of FIG. 3, and a toothed operator or pinion 174 is journaled in a tool holder 124 which carried the tool 123. As may be seen in FIG. 9, the pinion overlies the threaded bar 170 and is rotated by means of a knurled knob 175 on the back of the holder 124. With this structure, the tool holder 124 may be smoothly displaced in alternate rightward and leftward directions simply by rotating the knob 175 in the desired directions.

In another embodiment of the present invention, a frame structure 225 (FIGS. 10 and 11, Sheet 3) is provided having modified guide means which keeps its arms 227 and 228 disposed in proper parallel relation when the arm spacing is being adjusted. To this end, the guide means comprises a solid, elongated member or rod 226 mounting the arms 227 and 228 in spaced relation thereon to form a U-shaped frame which mounts on the ends ofa grinder shaft 213 as illustrated in FIG. 10. The rod 226 is square in cross section and has flats 226a, 226a on its periphery which slidably engage in square apertures in the arms 227 and 228, thereby preventing angular displacement therebetween but permitting axial displacement therethrough.

In order to releasably lock the arms 227 and 228 in selected locations on the bar 226, each arm, for example, the righthand arm 228, has a lowerjaw 204 (FIG. 15) and an upperjaw 205 in its rearward end, the jaws being connected together by means of a threaded fastener 206 threaded into the top of the arm 228. As may be seen in FIGS. 10 and 11, the left-hand arm 227 is similarly constructed. With this structure, the fastener 206 is operable upon rotation in opposite directions to cause the jaws 204 and 205 to engage and disengage the rod 226 and thereby enable the arm spacing to be adjusted without having the arms pivot out of their parallel relation.

In the embodiment of FIGS. 10-15, a modified tool holder 224 is provided in accordance with the present invention. As may be seen in FIGS. 13-14, the tool holder 224 has approached guideway 22612 therethrough which communicates at its upper end with a lubricant fitting 208 through a vertically disposed passage 209. In this embodiment, a dressing tool 223 is carried underneath the guide rod 226 and is mounted for adjustment into and out of the holder 224 in a manner similar to the tool 23 in the first-described embodiment; however, the tool 223 is prevented from rotating in its holder 224 when its operator 280 is being rotated by means of flats which extend lengthwise along its body and which engage mating surfaces in the holder. Foreign matter is prevented from entering the recess in which the tool is mounted in the holder by means of a flexible wiper 290 surrounding the body of the tool and secured to the front of the holder 224 by means of an apertured plate 291 which is clamped thereto by means of bolts 292, 292.

In this embodiment, the tool holder has a pair of closely spaced webs 273, 273 on its rearward end which project upwardly therefrom and each of which has a through bore through which a threaded bar 270 passes. An internally threaded and externally knurled operator or wheel 274 is rotatably mounted between the webs 273, 273 and threadedly engages the bar 270 so that when the wheel 274 is rotated clockwise (FIG. 12), the tool holder 224 is displaced leftward, and when the wheel 274 is rotated counterclockwise, the tool holder is displaced rightward. As may be seen in FIG. 13, a pair of resilient annular wipers 276, 276 are mounted in recesses on opposite sides of the wheel 274 to surround the threaded bar 270 inwardly of the webs 273, 273 for preventing foreign matter from wearing the bar 270 and the wheel 274. Thus, with this structure, the tool holder 224 may be displaced on its guide means simply by rotating the wheel 274 in the desired direction.

It should be apparent that wheel dressing with the modified apparatus is effected in a manner similar to the manner in which the first described apparatus is employed. However, in the embodiment of FIGS. 10-44, it is necessary for the arm spacing to be adjusted as the frame is mounted on the guider since. unlike the embodiment of FIG. 3, the centering pins may not be displaced toward or away from their mounting arms for increasing the spacing between their apexes.

In view of the foregoing, it should be apparent that novel apparatus has now been provided for dressing grinding wheels in a simple and expeditious manner.

While preferred embodiments of the present invention have been described in detail, various modifications, alterations or changes may be made without departing from the spirit and scope of the present invention.

What we claim is:

1. Apparatus for performing operations on the periphery of a rotary member mounted on a shaft having a central axis of rotation, comprising:

a tool for engaging said periphery,

a holder for mounting said tool,

guide means slidably mounting said tool holder for displacement parallel to said axis,

a pair of arms carried in spaced-apart parallel relation on said guide means and projecting outwardly therefrom toward said shaft to form a U-shaped frame with said guide means,

bearing means mounted on each of said arms to engage said shaft and dispose said guide means parallel to said axis while permitting relative rotation between said shaft and said guide means, and

support means depending from said frame for limiting pivotal movement of said frame about said axis when said rotary member is rotated and said tool is operatively engaged therewith,

whereby the tool holder may be displacedacross the periphery of the rotary member to cause the tool to operate thereon.

2. Apparatus according to claim 1 wherein said guide means includes an aperture in each of said arms and an elongated member slidable in said apertures, and including releasable locking means carried on at least one of said arms to secure said one arm in selected locations on said member, whereby the spacing between the arms may be adjusted to enable the apparatus to accommodate shafts of various lengths.

3. Apparatus according to claim 2 including at least one flat surface on said member and at least one flat surface mating therewith in each of said apertures in said arms, whereby the surfaces interact to limit relative angular displacement between the arms.

4. Apparatus according to claim 2 including an elongated bar disposed parallel to said member and coextensive in length therewith, bore means slidably receiving said bar in each arm, means to anchor said bar on one of said arms, and means on the other of said arms to releasably lock said bar thereto, whereby the bar cooperates with said member and arms to limit angular displacement therebetween.

5. Apparatus according to claim 4 wherein said bar has external threads along a major portion of its length and including an operator mounted on said tool holder and engaging said threaded bar, and means to rotate said operator relative to said threaded bar, whereby said holder is displaced on said guide means upon said relative rotation of said operator and said bar.

6. Apparatus according to claim 5 wherein said holder has a pair of closely spaced webs projecting outwardly therefrom, each of said webs having a bore aligned with said threaded bar, said operator being cylindrical and having internal threads threadedly engaging said bar intermediate said webs for rotation relative to said holder, and said means to rotate said operator including knurls on the periphery of said operator.

7. Apparatus according to claim 5 wherein said holder has a way receiving said threaded rod and a bore intersecting said way normal thereto, said operator being journaled for rotation in said bore, and said operator having axially extending teeth engaging said threaded bar, and said means to rotate said operator including a knurled knob on said operator remote from said teeth.

8. Apparatus according to claim 1 including means mounting said tool in said tool holder for displacement transversely to its normal path of movement on said guide means and into and out of operative engagement with said periphery; said tool mounting means comprising:

a recess opening outwardly toward said shaft to slidably receive said tool,

a threaded element threadedly engaging said tool and engaging said holder, said element being operable upon rotation in selected opposite directions to cause said tool to advance inwardly and outwardly of said recess,

whereby the depth of engagement between the tool and the periphery of the rotary member may be varied.

9. Apparatus according to claim 8 wherein said tool has an internally threaded rearwardly opening bore and said element has external threads threadedly engaging in said threaded bore, and including antirotation means on said holder for cooperating with said tool for preventing it from rotating in its mounting recess upon rotation of said element.

10. Apparatus according to claim 9 wherein said antirotation means includes at least one flat surface on said tool and at least one flat surface in said tool mounting recess for mating therewith to thereby prevent rotation ofsaid tool therein.

11 Apparatus according to claim 9 wherein said antirotation means includes an elongated slot extending lengthwise in the surface of said tool, and a screw threaded into said holder and engaging in said slot, and including an abutment at each end of said slot for engaging said screw upon continued rotation of said element to arrest axial displacement of said tool in its recess.

12. Apparatus according to claim 1 including means to removably mount said bearing means in aligned spaced confronting relation at selected locations on said arms, comprising:

a stem projecting from each of said bearings means, each of said arms having a series of transverse bores for receiving said stems, and

means releasably latching said stems in said transverse bores, whereby the bearing means may be mounted at selected locations on the arms.

13. Apparatus according to claim 12 wherein said stemlatching means includes a channel having a transversely extending portion and a rearwardly opening longitudinally extending portion in the periphery of each stem, a dog disposed in each of said transverse bores and projecting into said channel to normally engage in said transversely extending portion, and resilient means engaging between each arm and said bearing means to normally bias said bearing means forwardly and said transverse channel portion against said dog.

14. Apparatus according to claim 13 wherein one of said stems has a portion ofits channel extending forwardly from its transverse portion and the resilient means associated with said one stem includes a compression spring, so that said one stem may be displaced toward and away from its mounting arm for displacing said bearing means axially of said shaft.

15. Apparatus according to claim 1 wherein said shaft has a central cavity in each of its ends, and said bearing means includes a conical needle member for engaging in said central cavity and an antifriction bearing mounting said conical member for rotation on its associated arm, whereby the guide means may be mounted quickly and accurately in proper registry with the shaft.

16. Apparatus according to claim 1 wherein said support means includes a depending strut and clamping means carrying said strut and releasably engaging said guide means,

whereby the strut may be mounted at selected locations on the guide means.

17. Apparatus according to claim 16 wherein said strut includes a support shaft having external threads thereon, a yoke pivotally connected to said clamping means and having internal threads threadedly engaging said support shaft, and a nut engaging said support shaft and said yoke to releasably lock said support shaft in selected locations in said yoke, whereby the elevation at which the guide means is supported may be adjusted. 

1. Apparatus for performing operations on the periphery of a rotary member mounted on a shaft having a central axis of rotation, comprising: a tool for engaging said periphery, a holder for mounting said tool, guide means slidably mounting said tool holder for displacement parallel to said axis, a pair of arms carried in spaced-apart parallel relation on said guide means and projecting outwardly therefrom toward said shaft to form a U-shaped frame with said guide means, bearing means mounted on each of said arms to engage said shaft and dispose said guide means parallel to said axis while permitting relative rotation Between said shaft and said guide means, and support means depending from said frame for limiting pivotal movement of said frame about said axis when said rotary member is rotated and said tool is operatively engaged therewith, whereby the tool holder may be displaced across the periphery of the rotary member to cause the tool to operate thereon.
 2. Apparatus according to claim 1 wherein said guide means includes an aperture in each of said arms and an elongated member slidable in said apertures, and including releasable locking means carried on at least one of said arms to secure said one arm in selected locations on said member, whereby the spacing between the arms may be adjusted to enable the apparatus to accommodate shafts of various lengths.
 3. Apparatus according to claim 2 including at least one flat surface on said member and at least one flat surface mating therewith in each of said apertures in said arms, whereby the surfaces interact to limit relative angular displacement between the arms.
 4. Apparatus according to claim 2 including an elongated bar disposed parallel to said member and coextensive in length therewith, bore means slidably receiving said bar in each arm, means to anchor said bar on one of said arms, and means on the other of said arms to releasably lock said bar thereto, whereby the bar cooperates with said member and arms to limit angular displacement therebetween.
 5. Apparatus according to claim 4 wherein said bar has external threads along a major portion of its length and including an operator mounted on said tool holder and engaging said threaded bar, and means to rotate said operator relative to said threaded bar, whereby said holder is displaced on said guide means upon said relative rotation of said operator and said bar.
 6. Apparatus according to claim 5 wherein said holder has a pair of closely spaced webs projecting outwardly therefrom, each of said webs having a bore aligned with said threaded bar, said operator being cylindrical and having internal threads threadedly engaging said bar intermediate said webs for rotation relative to said holder, and said means to rotate said operator including knurls on the periphery of said operator.
 7. Apparatus according to claim 5 wherein said holder has a way receiving said threaded rod and a bore intersecting said way normal thereto, said operator being journaled for rotation in said bore, and said operator having axially extending teeth engaging said threaded bar, and said means to rotate said operator including a knurled knob on said operator remote from said teeth.
 8. Apparatus according to claim 1 including means mounting said tool in said tool holder for displacement transversely to its normal path of movement on said guide means and into and out of operative engagement with said periphery; said tool mounting means comprising: a recess opening outwardly toward said shaft to slidably receive said tool, a threaded element threadedly engaging said tool and engaging said holder, said element being operable upon rotation in selected opposite directions to cause said tool to advance inwardly and outwardly of said recess, whereby the depth of engagement between the tool and the periphery of the rotary member may be varied.
 9. Apparatus according to claim 8 wherein said tool has an internally threaded rearwardly opening bore and said element has external threads threadedly engaging in said threaded bore, and including antirotation means on said holder for cooperating with said tool for preventing it from rotating in its mounting recess upon rotation of said element.
 10. Apparatus according to claim 9 wherein said antirotation means includes at least one flat surface on said tool and at least one flat surface in said tool mounting recess for mating therewith to thereby prevent rotation of said tool therein.
 11. Apparatus according to claim 9 wherein said antirotation means includes an elongated slot extending lengthwise in the surface of said tool, and a screw threaded into said holder and engaging in said slot, and including an abutment at each end of said slot for engaging said screw upon continued rotation of said element to arrest axial displacement of said tool in its recess.
 12. Apparatus according to claim 1 including means to removably mount said bearing means in aligned spaced confronting relation at selected locations on said arms, comprising: a stem projecting from each of said bearings means, each of said arms having a series of transverse bores for receiving said stems, and means releasably latching said stems in said transverse bores, whereby the bearing means may be mounted at selected locations on the arms.
 13. Apparatus according to claim 12 wherein said stem-latching means includes a channel having a transversely extending portion and a rearwardly opening longitudinally extending portion in the periphery of each stem, a dog disposed in each of said transverse bores and projecting into said channel to normally engage in said transversely extending portion, and resilient means engaging between each arm and said bearing means to normally bias said bearing means forwardly and said transverse channel portion against said dog.
 14. Apparatus according to claim 13 wherein one of said stems has a portion of its channel extending forwardly from its transverse portion and the resilient means associated with said one stem includes a compression spring, so that said one stem may be displaced toward and away from its mounting arm for displacing said bearing means axially of said shaft.
 15. Apparatus according to claim 1 wherein said shaft has a central cavity in each of its ends, and said bearing means includes a conical needle member for engaging in said central cavity and an antifriction bearing mounting said conical member for rotation on its associated arm, whereby the guide means may be mounted quickly and accurately in proper registry with the shaft.
 16. Apparatus according to claim 1 wherein said support means includes a depending strut and clamping means carrying said strut and releasably engaging said guide means, whereby the strut may be mounted at selected locations on the guide means.
 17. Apparatus according to claim 16 wherein said strut includes a support shaft having external threads thereon, a yoke pivotally connected to said clamping means and having internal threads threadedly engaging said support shaft, and a nut engaging said support shaft and said yoke to releasably lock said support shaft in selected locations in said yoke, whereby the elevation at which the guide means is supported may be adjusted. 